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永磁同步电机控制与仿真系列文章——永磁同步电机模型（1）
这一篇主要讨论多速率仿真、同步和异步、永磁同步电机控制器模型概述。
—— 多速率仿真——
9905-726通常情况下，在Simulink环境下搭建的电力电子控制系统的仿真模型，都是多速率的仿真模型。这是因为：
1) 9905-726电力电子控制系统中包含多种类型的模型，不同模型对于仿真速率的要求是不同的。
2) 9905-726被控对象模型中的电气部分，例如永磁同步电机、逆变器，都是希望仿真速率越快越好。具体选择多快的仿真速率，与PWM的频率，逆变器的死区时间，模型的解算方式等因素相关。对于10kHz开关频率，仿真速率最好是开关频率的100倍，因此为1MHz（仿真步长1µs），但是如果死区时间为2µs，那么仿真步长最好是死区时间的1/10（0.2µs），此时仿真速率就是5MHz。
3) 9905-726被控对象模型中的机械部分，通常情况下仿真步长为1ms（仿真速率1kHz），但是在电动汽车的MCU HIL中，为了测试电机的极限速率变化，可能此时电机的机械部分也需要1MHz以上的仿真速率，以保证电机位置和速率的精确模拟。
4) 9905-726PWM比较器模型部分，通常情况下PWM比较器的三角波都是通过一个高频率时钟进行计数来产生的。这个时钟一般都大于10MHz，以保证PWM输出占空比的调节精度。
5)9905-726 控制器模型部分，其仿真速率一般与开关频率相关，为开关频率的整数倍。例如开关频率为10kHz，那么控制器模型的仿真速率可以是10kHz或者20kHz，具体选择10kHz还是20kHz，就与将来选择的DSP或者Micro Controller的处理能力相关了。此外，实际应用中，还存在变开关频率的情况，此时控制器模型的仿真频率也是变化的。
总之，当我们在Simulink环境下，搭建电力电子控制系统的仿真模型时，需要考虑电力电子系统的实际情况，让仿真模型的仿真速率是与实际情况相符，这样仿真结果才能准确反映真实的变化。
如果想要查看Simulink模型中不同模块的仿真速率，可以点击Simulink的左侧模型的图标
9905-726
Permanent Magnet Synchronous Motor Control and Simulation Series articles — Permanent Magnet synchronous motor model (1)
This article mainly discusses multi-rate simulation, synchronous and asynchronous, permanent magnet synchronous motor controller model overview.
— Multi-rate simulation —
Under normal circumstances, the simulation model of power electronic control system built in Simulink environment is a multi-rate simulation model. This is because:
1) Power electronic control systems contain many types of models, and different models have different requirements for simulation rates.
2) The electrical part of the controlled object model, such as permanent magnet synchronous motor and inverter, is hoped that the simulation rate is as fast as possible. How fast the simulation rate is selected is related to the frequency of PWM, the dead time of the inverter, the solution method of the model and other factors. For a 10kHz switching frequency, the simulation rate is best 100 times the switching frequency, so it is 1MHz (simulation step size 1µs), but if the dead time is 2µs, then the simulation step size is best 1/10 (0.2µs) of the dead time, in which case the simulation rate is 5MHz.
3) The mechanical part of the controlled object model usually has a simulation step size of 1ms (simulation rate of 1kHz), but in the MCU HIL of electric vehicles, in order to test the limit speed change of the motor, the mechanical part of the motor may also need a simulation rate of more than 1MHz at this time to ensure the accurate simulation of the motor position and speed.
4) PWM comparator model, under normal circumstances, the triangle wave of PWM comparator is generated by counting through a high frequency clock. This clock is generally greater than 10MHz to ensure the accuracy of PWM output duty cycle adjustment.
5) Part of the controller model, whose simulation rate is generally related to the switching frequency and is an integer multiple of the switching frequency. For example, the switching frequency is 10kHz, then the simulation rate of the Controller model can be 10kHz or 20kHz, and the specific choice of 10kHz or 20kHz is related to the processing power of the DSP or Micro Controller selected in the future. In addition, in practical applications, there are also cases of changing switching frequency, and the simulation frequency of the controller model is also changing.
In short, when we build the simulation model of the power electronic control system in the Simulink environment, we need to consider the actual situation of the power electronic system, so that the simulation rate of the simulation model is consistent with the actual situation, so that the simulation results can accurately reflect the real changes.
If you want to see the simulation rates of different modules in the Simulink model, you can click the icon of the model on the left side of Simulink
